Genes for C4b-binding protein alpha- and beta-chains (C4BPA and C4BPB) are located on chromosome 1, band 1q32, in humans and on chromosome 13 in rats
C4b-binding protein is involved in the regulation of the complement system. It is a multimeric protein composed of seven identical alpha-chains and a single copy of a unique beta-chain. The latter was identified only recently and its structure determined by cDNA cloning. Both subunits in C4b-binding protein belong to the same superfamily of proteins composed predominantly of tandemly arranged shor